Correct prototype of write_tex().

In a reverse of write_html(), write_tex() is declared with three
parameters, but only called with two.

Removing the third parameter is fine as it is unused.

nuweb.w

@@ -2055,10 +2055,9 @@ static void write_ArglistElement();
 The routine \verb|write_tex| takes two file names as parameters: the
 name of the web source file and the name of the \verb|.tex| output file.
 @o latex.c -cc -d
-@{void write_tex(file_name, tex_name, sector)
+@{void write_tex(file_name, tex_name)
      char *file_name;
      char *tex_name;
-     unsigned char sector;
 {
   FILE *tex_file = fopen(tex_name, "w");
   if (tex_file) {